A typhoon is a mature tropical cyclone that develops between 180° and
100°E in the Northern Hemisphere. This region is referred to as the
Northwestern Pacific Basin, and is the most active tropical cyclone
basin on Earth, accounting for almost one-third of the world's annual
tropical cyclones. For organizational purposes, the northern Pacific
Ocean is divided into three regions: the eastern (North America to
140°W), central (140° to 180°W), and western (180° to 100°E). The
Regional Specialized Meteorological Center
Regional Specialized Meteorological Center (RSMC) for tropical cyclone
forecasts is in Japan, with other tropical cyclone warning centers for
the northwest Pacific in
Hawaii (the Joint
Typhoon Warning Center),
Philippines and Hong Kong. While the RSMC names each system, the
main name list itself is coordinated among 18 countries that have
territories threatened by typhoons each year. Only the
their own naming list for systems approaching the country[citation
A typhoon differs from a cyclone or hurricane only on the basis of
location. A hurricane is a storm that occurs in the Atlantic Ocean
and northeastern Pacific Ocean, a typhoon occurs in the northwestern
Pacific Ocean, and a cyclone occurs in the south Pacific or Indian
Within the northwestern Pacific there are no official typhoon seasons
as tropical cyclones form throughout the year. Like any tropical
cyclone, there are six main requirements for typhoon formation and
development: sufficiently warm sea surface temperatures, atmospheric
instability, high humidity in the lower to middle levels of the
Coriolis force to develop a low pressure center, a
pre-existing low level focus or disturbance, and low vertical wind
shear. While the majority of storms form between June and November, a
few storms do occur between December and May (although tropical
cyclone formation is at a minimum during that time). On average, the
northwestern Pacific features the most numerous and intense tropical
cyclones globally. Like other basins, they are steered by the
subtropical ridge towards the west or northwest, with some systems
recurving near and east of Japan. The
Philippines receive the brunt of
the landfalls, with
Japan being impacted slightly less. Some
of the deadliest typhoons in history have struck China. Southern China
has the longest record of typhoon impacts for the region, with a
thousand-year sample via documents within their archives.
received the wettest known typhoon on record for the northwest Pacific
tropical cyclone basins.
1.1 Etymology and usage
1.2 Intensity classifications
4 Basin monitoring
4.1 Name sources
6 See also
8 External links
Etymology and usage
The term typhoon is the regional name in the northwest Pacific for a
severe (or mature) tropical cyclone, whereas hurricane is the
regional term in the northeast Pacific and northern Atlantic.
Elsewhere this is called a tropical cyclone, severe tropical cyclone,
or severe cyclonic storm.
The Oxford English Dictionary cites
Urdu ṭūfān and Chinese tai
fung giving rise to several early forms in English. The earliest forms
-- "touffon", later "tufan", "tuffon", and others -- derive from Urdu
ṭūfān, with citations as early as 1588. From 1699 appears
"tuffoon", later "tiffoon", derived from Chinese with spelling
influenced by the older Urdu-derived forms. The modern spelling
"typhoon" dates to 1820, preceded by "tay-fun" in 1771 and "ty-foong",
all derived from the Chinese tai fung.
Urdu source word توفان ṭūfān ("violent storm"; cognate to
Hindi तूफ़ान (tūfān)) comes from the Persian
(Persian: توفان/طوفان tūfān meaning "storm" which comes
from the verb (Persian: توفیدن/طوفیدن tūfīdan
(Persian: توفیدن/طوفیدن, "to roar, to blow
furiously"). The word طوفان (ṭūfān) is also
derived from Arabic as coming from ṭāfa, to turn round.
The Chinese source is the word tai fung or Taifeng (simplified
Chinese: 台风; traditional Chinese: 颱風; pinyin: táifēng),
cited as a common dialect form of Mandarin dà "big" and fēng
"wind". In Mandarin the word for the windstorm is 大风 (dàfēng,
"big wind") and in
Cantonese 大風 (daai6 fung1, "big wind"). The
modern Japanese word, 台風 (たいふう, taifuu), is also derived
from Chinese. The first character is normally used to mean "pedestal"
or "stand", but is actually a simplification of the older kanji 颱,
which means "typhoon"; thus the word originally meant "typhoon wind".
Ancient Greek Τυφῶν (Tuphôn, Typhon) is not unrelated and
has secondarily contaminated the word. The Persian and Chinese
terms may originally have been derived from the Greek word.
RSMC Tokyo's Tropical Cyclone Intensity Scale
Very Strong Typhoon
Severe Tropical Storm
Tropical cyclone scales
A tropical depression is the lowest category that the Japan
Meteorological Agency uses and is the term used for a tropical system
that has wind speeds not exceeding 33 knots (38 mph;
61 km/h). A tropical depression is upgraded to a tropical
storm should its sustained wind speeds exceed 34 knots (39 mph;
63 km/h). Tropical storms also receive official names from RSMC
Tokyo. Should the storm intensify further and reach sustained wind
speeds of 48 knots (55 mph; 89 km/h) then it will be
classified as a severe tropical storm. Once the system's maximum
sustained winds reach wind speeds of 64 knots (74 mph;
119 km/h), the JMA will designate the tropical cyclone as a
typhoon—the highest category on its scale.
From 2009 the
Hong Kong Observatory started to further divide typhoons
into three different classifications: typhoon, severe typhoon and
super typhoon. A typhoon has wind speed of 64-79 knots
(73-91 mph; 118–149 km/h), a severe typhoon has winds of
at least 80 knots (92 mph; 150 km/h), and a super typhoon
has winds of at least 100 knots (120 mph; 190 km/h). The
Joint Typhoon Warning Center
Joint Typhoon Warning Center (JTWC) unofficially
classifies typhoons with wind speeds of at least 130 knots
(67 m/s; 150 mph; 241 km/h)—the equivalent of a
strong Category 4 storm in the Saffir-Simpson scale—as super
typhoons. However, the maximum sustained wind speed measurements
that the JTWC uses are based on a 1-minute averaging period, akin to
National Hurricane Center
National Hurricane Center and Central Pacific Hurricane
Center. As a result, the JTWC's wind reports are higher than JMA's
measurements, as the latter are based on a 10-minute averaging
Depth of 26 °C isotherm on October 1, 2006
See also: Tropical cyclogenesis
There are six main requirements for tropical cyclogenesis:
sufficiently warm sea surface temperatures, atmospheric instability,
high humidity in the lower to middle levels of the troposphere, enough
Coriolis force to develop a low pressure center, a pre-existing low
level focus or disturbance, and low vertical wind shear. While these
conditions are necessary for tropical cyclone formation, they do not
guarantee that a tropical cyclone will form. Normally, an ocean
temperature of 26.5 °C (79.7 °F) spanning through a depth
of at least 50 metres (160 ft) is considered the minimum to
maintain the special mesocyclone that is the tropical
cyclone. These warm waters are needed to maintain the
warm core that fuels tropical systems. A minimum distance of
500 km (300 mi) from the equator is normally needed for
tropical cyclogenesis. Even with perfect upper level conditions
and the required atmospheric instability, the lack of a surface focus
will prevent the development of organized convection and a surface
low. Vertical wind shear of less than 10 m/s (20 kn,
33 ft/s) between the ocean surface and the tropopause is required
for tropical cyclone development. Typically with Pacific typhoons,
there are two outflow jets: one to the north ahead of an upper trough
in the Westerlies, and a second towards the equator.
In general, westerly wind increases associated with the
Madden–Julian oscillation lead to increased tropical cyclogenesis in
all tropical cyclone basins. As the oscillation propagates from west
to east, it leads to an eastward march in tropical cyclogenesis with
time during that hemisphere's summer season. On average, twice per
year twin tropical cyclones will form in the western Pacific Ocean,
5th parallel north
5th parallel north and the 5th parallel south, along the same
meridian, or line of longitude. There is an inverse relationship
between tropical cyclone activity in the western Pacific basin and the
north Atlantic basin, however. When one basin is active, the other is
normally quiet, and vice versa. The main reason for this appears to be
the phase of the Madden–Julian oscillation, or MJO, which is
normally in opposite modes between the two basins at any given
Tropical storms and Typhoons by month,
for the period 1959–2015 (Northwest Pacific)
Nearly one-third of the world's tropical cyclones form within the
western Pacific. This makes this basin the most active on Earth.
Pacific typhoons have formed year round, with peak months from August
to October. The peak months correspond to that of the Atlantic
hurricane seasons. Along with a high storm frequency, this basin also
features the most globally intense storms on record. One of the most
recent busy seasons was 2013. Tropical cyclones form in any month of
the year across the northwest Pacific Ocean, and concentrate around
June and November in the northern Indian Ocean. The area just
northeast of the
Philippines is the most active place on
tropical cyclones to exist. Across the
activity reaches a minimum in February, before increasing steadily
through June, and spiking from July through October, with September
being the most active month for tropical cyclones across the
archipelago. Activity falls off significantly in November, although
Typhoon Haiyan, the strongest Philippine typhoon on record, was a
November typhoon. The most frequently impacted areas of the
Philippines by tropical cyclones are northern and central
eastern Visayas. A ten-year average of satellite determined
precipitation showed that at least 30 percent of the annual
rainfall in the northern
Philippines could be traced to tropical
cyclones, while the southern islands receive less than 10 percent
of their annual rainfall from tropical cyclones. The genesis and
intensity of typhoons are also modulated by slow variation of the sea
surface temperature and circulation features following a near-10-year
See also: Hurricane Belt
Tracks of all tropical cyclones in the northernwestern Pacific Ocean
between 1980 and 2005. The vertical line to the right is the
International Date Line.
Most tropical cyclones form on the side of the subtropical ridge
closer to the equator, then move poleward past the ridge axis before
recurving north and northeast into the main belt of the
Westerlies. When the subtropical ridge shifts due to El Niño, so
will the preferred tropical cyclone tracks. Areas west of
Korea tend to experience many fewer September–November tropical
cyclone impacts during El Niño and neutral years. During El Niño
years, the break in the subtropical ridge tends to lie near 130°E,
which would favor the Japanese archipelago. During La Niña years,
the formation of tropical cyclones, and the subtropical ridge
position, shift westward across the western Pacific Ocean, which
increases the landfall threat to
China and greater intensity to
Philippines. Those that form near the
Marshall Islands find their
way to Jeju Island, Korea.
Typhoon paths follow three general directions.
Straight track (or straight runner). A general westward path affects
the Philippines, southern China, Taiwan, and Vietnam.
A parabolic recurving track. Storms recurving affect eastern
Philippines, eastern China, Taiwan, Korea, Japan, and the Russian Far
Northward track. From point of origin, the storm follows a northerly
direction, only affecting small islands.
A rare few storms, like Hurricane John, were redesignated as typhoons
as they originated in the Eastern/Central Pacific and moved into the
Within the Western Pacific, RSMC Tokyo-
Typhoon Center, part of the
Japan Meteorological Agency has had the official warning
responsibility for the whole of the Western Pacific since 1989,
and the naming responsibility for systems of tropical storm strength
or greater since 2000. However each National Meteorological and
Hydrological Service within the western Pacific has the responsibility
for issuing warnings for land areas about tropical cyclones affecting
their country, such as the
Joint Typhoon Warning Center
Joint Typhoon Warning Center for United
States agencies, the Philippine Atmospheric, Geophysical and
Astronomical Services Administration (PAGASA) for interests in the
island archipelago nation, and the
Hong Kong Observatory for
storms that come close enough to cause the issuance of warning
The list of names consists of entries from 17 Southeast and East Asian
nations and the
United States who have territories directly affected
by typhoons. The submitted names are arranged into five lists, and
each list is cycled with each year. Unlike tropical cyclones in other
parts of the world, typhoons are not named after people. Instead, they
generally refer to animals, flowers, astrological signs, and a few
personal names. However, PAGASA retains its own naming list, which
does consist of human names. Therefore, a typhoon can possibly
have two names. Storms that cross the date line from the central
Pacific retain their original name, but the designation of hurricane
becomes typhoon. In Japan, people use the numerical designation of
typhoons according to the sequence of their occurrence in the calendar
The most active Western Pacific typhoon season was in 1964,[citation
needed] when 39 storms of tropical storm strength formed. Only 15
seasons had 30 or more storms developing since reliable records began.
The least activity seen in the northwest
Pacific Ocean was during the
2010 Pacific typhoon season, when only 14 tropical storms and
seven typhoons formed. In the Philippines, the most active season,
since 1945, for tropical cyclone strikes was 1993 when nineteen
tropical cyclones moved through the country. There was only one
tropical cyclone that moved through the
Philippines in 1958. The
2004 Pacific typhoon season
2004 Pacific typhoon season was the busiest for Okinawa since
Guangdong in southern China, during the past thousand
years, the most active decades for typhoon strikes were the 1660s and
The highest reliably-estimated maximum sustained winds on record for a
typhoon were those of
Typhoon Haiyan at 195 miles per hour
(314 km/h) shortly before its landfall in the central Philippines
on Nov. 8, 2013. The most intense storm based on minimum pressure
Typhoon Tip in the northwestern
Pacific Ocean in 1979, which
reached a minimum pressure of 870 hectopascals (26 inHg) and
maximum sustained wind speeds of 165 knots (85 m/s,
190 mph, 310 km/h). The deadliest typhoon of the 20th
Typhoon Nina, which killed nearly 100,000 in
China in 1975
due to a flood that caused 12 reservoirs to fail. After Typhoon
Morakot landed in
Taiwan at midnight on August 8, 2009, almost the
entire southern region of
Taiwan (Chiayi County/Chiayi City, Tainan
Tainan City (now merged as Tainan), Kaohsiung County/Kaohsiung
City (now merged as Kaohsiung), and Pingtung County) and parts of
Taitung County and
Nantou County were flooded by record-breaking heavy
rain. The rainfall in
Pingtung County reached 2,327 millimeters
(91.6 in), breaking all rainfall records of any single place
Taiwan induced by a single typhoon, and making the cyclone the
wettest known typhoon.
Tropical cyclones portal
China tropical cyclone rainfall climatology
Effects of tropical cyclones
Typhoons in the Philippines
2018 Pacific typhoon season
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